New gene sequences are discovered daily, and advanced molecular biological techniques are revolutionizing clinical practice in genetic disorders, oncology, infections diseases, etc. . . . Although the current major focus is on using DNA to identify disease genes, mutations, and translocations, or foreign genes as infection agents, the quantification of various specific mRNA molecules in cells and tissues is an attractive field in diagnostic molecular pathology. The concentrations of each specific mRNA are different in normal and disease states and change rapidly in response to various clinical treatments. Among the technologies for assays of mRNA are Northern blotting,1 RNase protection assay,2 reverse transcription followed by polymerase chain reaction (RT-PCR),3,4 in situ hybridization 5 and in situ PCR.6 Currently, a variety of detection labels can be used, e.g. radioisotopes, fluorescence,7 and chemiluminescence.8 Furthermore, once mRNA is reverse-transcribed into cDNA, various gene amplification techniques9-11 may be applicable. However, because each assay has its own problems, no assay has been accepted as routine for molecular diagnostic purposes; and none of these assays allows researchers to use conventional colorimetric Enzyme-Linked Immunosorbent Assay (ELISA) meters, which are widely available in any laboratory.
To address the above mentioned problem, the important task is to identify a procedure to measure specific mRNA for the molecular diagnosis of genetic disorders. Among a variety of genetics disorders, the spinal muscular atrophy (SMA) is a lethal autosomal recessive disease affecting 1 in 6,000 newborns, and is one of the most common genetic causes of death in childhood.12-14 SMA is characterised by degeneration of motoneurons from the ventral horns of the spinal cord, leading to symmetrical paralysis of volontary muscles with muscular atrophy. Three different clinical syndromes of SMA (SMA types I, II, and III) can be defined on the basis of age of onset, milestones of development, and age of survival.15 
All three types of SMA map to chomosome 5q13.3. Recently, Lefebvre et al.16 identified the SMN gene (Survival Motor Neuron, TBCD541) with 8 exons extending over approximately 20 kb. There is a high homologous copy of this gene in the centromeric repeating unit (CBCD541); this copy is present in 95.5% of control and hampers detection of absence of the SMN gene. The SMN gene and its centromeric copy differ in their exons by only two base pairs, one in exon 7 and one in exon 8; this difference thus allows the distinction of the SMN gene from its centromeric copy by single-strand conformation polymorphism (SSCP) analysis16 or by the use of the restriction enzymes.17 The SMN gene was either absent or interrupted in its exons 7 and 8 in the majority of patients (98%), independent of the type of SMA.16 
The qualitative techniques for molecular diagnosis of SMA at the DNA level using the SSCP technique16 and the restriction enzymes17 have actually become feassible by looking at the presence or absence of exons 7 and 8 of the SMN gene on chromosome 5q13.3. However, these detection methods are hazardous because they use a mutagenic compound (ethidium bromide) for the analysis of the PCR results. In an attempt to overcome this problem, the focus of this research is to develop a quantitative method for the molecular diagnosis of SMA by using the labeled nucleotide probes (labeling with 32P-dCTP and with biotin) in both the procedure using radioactive material and the Enzyme-Linked Immunosorbent Assay (ELISA) nonradioactive method for the measurement of specific mRNA. Both exons 7 and 8 of the SMN gene are checked for the diagnosis. The sample used for analysis can be either a biological fluid such as whole blood, or a fraction of cells or tissue, in which the RNA can be isolated. In this study, as described herein, are procedures which utilize human muscle cells from muscle biopsies for analysis.